Structural highlights
FunctionRS13_BACSU Located at the top of the head of the 30S subunit, it contacts several helices of the 16S rRNA. In the 70S ribosome it contacts the 23S rRNA (bridge B1a) and protein L5 of the 50S subunit (bridge B1b), connecting the 2 subunits; these bridges are implicated in subunit movement. Contacts the tRNAs in the A and P-sites.[HAMAP-Rule:MF_01315] Publication Abstract from PubMedStalled ribosomes are rescued by pathways that recycle the ribosome and target the nascent polypeptide for degradation. In E. coli, these pathways are triggered by ribosome collisions through the recruitment of SmrB, a nuclease that cleaves the mRNA. In B. subtilis, the related protein MutS2 was recently implicated in ribosome rescue. Here we show that MutS2 is recruited to collisions by its SMR and KOW domains, and we reveal the interaction of these domains with collided ribosomes by cryo-EM. Using a combination of in vivo and in vitro approaches, we show that MutS2 uses its ABC ATPase activity to split ribosomes, targeting the nascent peptide for degradation through the ribosome quality control pathway. However, unlike SmrB, which cleaves mRNA in E. coli, we see no evidence that MutS2 mediates mRNA cleavage or promotes ribosome rescue by tmRNA. These findings clarify the biochemical and cellular roles of MutS2 in ribosome rescue in B. subtilis and raise questions about how these pathways function differently in diverse bacteria. B. subtilis MutS2 splits stalled ribosomes into subunits without mRNA cleavage.,Park EN, Mackens-Kiani T, Berhane R, Esser H, Erdenebat C, Burroughs AM, Berninghausen O, Aravind L, Beckmann R, Green R, Buskirk AR EMBO J. 2024 Feb;43(4):484-506. doi: 10.1038/s44318-023-00010-3. Epub 2023 Dec , 14. PMID:38177497[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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